Toggle clamp



June 13, 1961 E S AL 2,988,122

TOGGLE CLAMP Filed March 2, 1959 2 Sheets-Sheet 1 Fig. 5 74 INVENTORS.

NORMAN C. STEVENS LOUIS R. RIECHEL may, & mow

J1me 1961 N. c. STEVENS ETAL 2,988,122

TOGGLE CLAMP 2 Sheets-Sheet 2 Filed March 2, 1959 Fig. 7

INVENTORS. NORMAN C. STEVENS LOUIS R RIECHEL BY 142m & jcnax United States Patent 2,988,122 TOGGLE CLAMP Norman C. Stevens and Louis R. Riechel, San Diego, Calif; said Rieehel assignor to said Stevens Filed Mar. 2, 1959, Ser. No. 796,533 3 Claims. (Cl. 144-290) The present invention relates generally to clamps and more particularly to a toggle clamp.

The primary object of this invention is to provide a toggle clamp which combines the quick toggle action initial clamping with positive and quickly attained screw adjustment to any desired degree of tightness after the clamp is locked in place.

Another object of this invention is to provide a toggle clamp having self-contained stop elements which ensure locking of the clamp at the proper position for repeatable, accurately controlled pressure.

Another object of this invention is to provide a toggle clamp which is adjustable over a wide range to hold various sizes and shapes of articles.

A further object of this invention is to provide a toggle clamp which can be released by a quick, simple motion without the excess of effort normally required to unlock such a clamp.

Still another object of this invention is to provide a toggle clamp which is easily attached to any convenient working surface or may be used on standard T-slot ma chine tool beds.

Another object of this invention is to provide a toggle clamp which is practicable and inexpensive to manufacture.

Finally, it is an object to provide a toggle clamp of the aforementioned character which is simple and convenient to use and which will give generally efiicient and durable service.

With these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully described in the specification, particu larly pointed out in the claims, and illustrated in the drawings which form a material part of this disclosure, and in which:

FIGURE 1 is a side elevation view of the clamp mounted on a work surface;

FIGURE 2 is a top plan view of the clamp;

FIGURE 3 is a sectional view taken on the line 3-3 of FIGURE 1;

FIGURE 4 is a fragmentary side elevation view showing an alternative base structure;

FIGURE 5 is a sectional view taken on the line 5-5 of FIGURE 4;

FIGURE 6 is a sectional view taken on the line 6-6 of FIGURE 2, but showing the clamp open; and

FIGURE 7 is a side elevation view of the clamp locked against a work piece below the surface on which the clamp is mounted.

Similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawings.

The clamp comprises a rigid, unitary frame 10 made from heavy gauge sheet material and having a pair of upright side plates 12 interconnected at their rear vertical edges by a back plate 14, the lower edges of said side plates having outwardly extending, horizontal base flanges 16. Mounted in the frame 10 is a clamp member 18 comprising a pair of parallel, flat plate elements 20 joined and spaced by a U-bracket 22, welded or otherwise sesured in place. The plate elements 20 are pivotally attached close to one pair of ends thereof to the side plates 12 by means of large rivets or pins 24 located adjacent the lower front corners of said side plates. The plate elements 20 have substantially arcuate cam edges 26 extending from the pins 24 to the free ends of the plates, the purpose of the curved edges being hereinafter explained. At the ends remote from the pins 24, the plate elements 20 have integral arms 28 extending substantially normal thereto and making the plate elements generally L-shaped. Between the ends of the arms 28 is a pressure pad 30, shown as a simple rectangular block although the shape may vary, said pressure pad being secured by a bolt 32 and nut 34, by which the pad can be locked at any desired angle relative to the arms 28.

The side plates 12 extend upwardly beyond the back plate 14 to provide a pair of spaced lug portions 36 and attached to the inner faces of said lug portions are two identical links 38 held by hinge pins 40 to swing parallel to the side plates. Mounted between the free ends of links 38 is a cylindrical nut block 42, rotatable about the axis of its mounting pin 44. Threaded through the nut block 42 is a long screw or bolt 46 having a T-bar 48 at one end for easy manual operation. The other end of the bolt 46 has a reduced diameter plain shank 50 which extends through a thrust washer 51 and is freely axially rotatable in a bearing block 52, but is held against axial shifting by a formed end flange 54. The bearing block 52 is pivotally secured between the plate elements 20, at their bight portions 56 defined by the junctions of arms 28 with the main body of the plate elements, the bearing block being held by a pin 58 normal to the bolt 46.

The base of the frame 10 is provided with a reinforcing plate 60, welded or otherwise secured to the flanges 16, said flanges and reinforcing plate having suitable slotted holes 62 therein to receive cap screws 64, or the like, by which the clamp is secured to a work surface 66. The work surface 66 may be a bench, machine table, or the like, some types of machine tables having T-slots therein for attachment of various tool or fixtures. For such machines, the clamp may be fitted with a foot plate 68, as in FIGURES 4 and 5, said foot plate having a large end lug 70 in which is a bolt hole 72 to receive a T-bolt or similar fastener, the arrangement being well known. The foot plate 68 has parallel side bars 74 extending from the sides thereof to rest on top of the flanges 16 on either side of the side plates 12, said side bars being welded or otherwise secured to the flanges. The reinforcing plate 60 is omitted and the lug 70 is joggled downwardly to be coplanar with the lower faces of the flanges 16, so that the clamp rests fiat on a supporting surface.

In FIGURE 1, the clamp is represented as used to hold a Work piece 76 on the surface 66 by means of the pressure pad 30. The-bolt 46 is adjusted so that, when the pressure pad 30 engages the work piece 76, the bolt must be forced down beyond the axis of the link hinge pins 40 with an over-center action until the ends of the links 38 adjacent the pins 44 rest on the cam edges 26 of plate elements 20 and prevent further downward travel of the bolt. This over-center or toggle action firmly clamps the pressure pad 30 in place and the pressure can be quickly released by raising the bolt 46 above the hinge pins 40. In many types of toggle clamps, holding pressure is ad justed before clamping, usually at the pressure pad itself. To apply heavy pressure, considerable force is needed to push the clamp into the over-center or locked position and similar force is needed to unlock the clamp. With the clamp illustrated, a reasonable clamping pressure may be preset by adjustment of the bolt 46, so that the locking action can be accomplished with a minimum of effort. The initial pressure may provide sufficient holding power in many cases, without requiring excess force to lock the clamp. However, after the clamp is initially locked, the pressure can be increased as desired by turning the T-bar 48, the leverage involved being considerable. It has been found that extremely high clamping pressures can be obtained by this type of action, yet the clamp can be quickly released by loosening the bolt 46 and lifting the bolt to raise the pressure pad 30. Exact clamping pressures can be calculated in terms of turns or fractions of turns of the T-bar 48, according to the pitch of the screw thread on the bolt 46. The pressure pad 30 can be turned to bring its contact face parallel to the work piece 76 for maximum clamping action and to avoid marking the surface of the work piece, the nut 34 being tightened to hold the pad in place. A desired clamping pressure can be accurately repeated as often as required.

In the open position, the bolt 46 is pulled up and back, swinging the links 38 over the top of their hinge pins 40 and raising the clamp member 18 well clear of the work area. The links 38 rest on the upper edge of the back plate 14, which thus acts as a stop 78 to hold the clamp in its full open position and retain the bolt 46 in a convenient accessible position, as in FIGURE 6 and indicated in broken line in FIGURE 1.

The clamp can also be used to hold work below the level of the surface on which the clamp is mounted, as illustrated in FIGURE 7. This is particularly useful in assembly jigs or similar fixtures in which parts must be held in many different positions. The bolt 46 has ample adjustment to allow for below the base clamping and, if necessary, the forward edges of the lug portions '36 may be provided with notches 80/ to clear the pins 44. The cam edges 26 are shaped so that they stop the links 38 at the proper position, just after the bolt 46 passes below the hinge pins 40, regardless of the position of the pressure pad 30. Thus the cam edges 26 and the links 38 cooperate to provide a stopping action immediately as the bolt 46 reaches final locking or clamped position. By using this type of action, the actual clamping pressure can be accurately controlled at all positions of the clamp, while the pressure may be subsequently increased by tightening the bolt 46.

The clamp may be made in any convenient size. To avoid extreme metal thicknesses in larger sizes, the links 38 may be in double pairs, additional links being attached to the respective hinge pins on the outside of the lug portions 36 for extra strength.

The operation of this invention will be clearly comprehended from a consideration of the foregoing description of the mechanical details thereof, taken in connection with the drawings and the above recited objects. It will be obvious that all said objects are amply achieved by this invention.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawings are to be considered as merely illustrative rather than limiting.

We claim:

1. A toggle clamp, comprising: a rigid frame having a base for attachment to a work surface; spaced, parallel side plates extending upwardly from said base; a clamp member pivotally mounted at one end between said side plates adjacent said base; the other end of said clamp member having a work engaging pad secured therein; a screw threaded bolt rotatably and pivotally attached at one end to said clamp member between the ends thereof; links pivotally attached at one end to the upper ends of said side plates; a nut block pivotally attached to the other ends of said links and through which said bolt is threaded; said clamp member having extended stop portions positioned to engage and stop said links when said bolt is shifted downwardly beyond the pivotal axis of said links on said side plates.

2. A toggle clamp, comprising: a rigid frame having a base for attachment to a work surface; spaced, parallel side plates extending upwardly from said base; a clamp member pivotally mounted at one end between said side plates adjacent said base; the other end of said clamp member having a work engaging pad secured therein; a screw threaded bolt rotatably and pivotally attached at one end to said clamp member between the ends thereof; links pivotally attached at one end to the upper ends of said side plates; a nut block pivotally attached to the other ends of said links and through which said bolt is threaded; the pivotal axes of said clamp member, said links, said nut block and said bolt at its attachment to the clamp member being parallel to each other and normal to the longitudinal axis of the bolt; said clamp member having extended stop portions positioned to engage and stop said links when said bolt is shifted downwardly beyond the pivotal axis of said links on said side plates.

3. A toggle clamp, comprising: a rigid frame having a base for attachment to a work surface; spaced, parallel side plates extending upwardly from said base; a clamp member pivotally mounted at one end between said side plates adjacent said base; the other end of said clamp member having a work engaging pad secured therein; a bearing block pivotally attached to said clamp member between the ends thereof; a screw threaded bolt axially rotatably mounted at one end in said bearing block and held against axial shifting therein; links pivotally attached at one end to the upper ends of said side plates; a nut block pivotally attached to the other ends of said links and through which said bolt is threaded; the pivotal axes of said clamp member, said links, said nut block and said bearing block being parallel to each other and normal to the longitudinal axis of said bolt; said clamp member having extended stop portions positioned to engage and stop said links'when said bolt is shifted downwardly beyond the pivotal axis of said links on said side plates.

References Cited in the file of this patent UNITED STATES PATENTS 2,103,074 Gardner Dec. 21, 1937 2,350,034 Herrington May 30, 1944 2,439,483 Merriman Apr. 13, 1948 2,600,584 Snall June 17, 1952 2,726,693 Saxton Dec. 13, 1955 2,744,552 Novick May 8, 1956 

